Machine tool for manufacturing aircraft wings



Dec. 25, 1945. n w. F. ProcH Erm.

Mmmm: fool, FOR MANUFACTURING AIRCRAFT WINGS I Filed May 13, 1944 3 Sheets-Sheet 1 uw. mw

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De. 25, i945.

w. F. `Ploczl-l ETAL MACHINE TOOL FOR MANUFACTURING AIRCRAFT WINGS A Filed' May 13|, 1944 s sheets-sheet 2 WFP/06H d. WM/srE/.E

I N VEN TOR5 Dec. 25, 1945 w. F. PlocH E-r AL MACHINE TOOL FOR MANUFACTURING AIRCRAFT WINGS Filed May 13, 1944 5 Sheets-Sheet 3 WEP/0c# I MM/sra:

myn/TOR. BY wn x/ Patented Dec. 25, 1945 MACHINE TOOL FOR MANUFACTURING AIRCRAFT WINGS William F. Piochvand John W. Mistcle, Detroit, Mich., assignors to uFord Motor Company, Dearborn, Mich., a corporation of Delaware Application May 13, 1944, Serial No. 535,428 s claims. (ci. zei-as) This invention relates to machine tools and manufacturing processes; and, more particularly, to a multipurpose tool which is advantageous in the machining of co-ordinated elements of ail'- craf-t wings.

The purpose of this invention'is to devise a multipurpose tool (referred to kherein as a milling machine," although it performs other operations as well) in which the Wing of an aircraft can be received in its substantial entirety and in which the numerous co-ordinated elementsrequiring further machinlng'can be iinished with ahigh degree of individual and interrelated'accuracy. Thus, the wing chosen as an example is a part' of a four-engine heavy bomber. is a continuous unitary structure extending through the aircraft fuselage, supports the four engines and the arcrafts landing gear. These components are releasably attached to suitable forgings which form an integral part of the wing fabric. In Work of this scale, .these points of attachment are separated by considerablel distances (as high as 60 feet) and their attaching surfaces are located in different and 'oblique planes. Nevertheless, it is necessary not only that these individual points be finished to a high degree of accuracy per sebuit also that eachpoint (and there are a plurality of such points forthe attachment of each separate component) be precisely related to the other points for the particular component and to the groups used in attaching the other components.

Thus, in the present instance, there arebasically-four engine attachment groups, each including four engine mountingvpad forgings and two landing gear groups, each comprising five bushing forgings. Each pad and bushing requires a number of separate nishing operations.,V

including milling, drilling, boring, reaming and spot facing. I Individually, these elements can be handled without particular diiculty by' conventional techniques. However, these' elements represent the points of application of the principal forces imposed on'the fabric.- The Wing structure has been carefully designed to *with*` ings, may result in binding, impeding' the free movement of the parts. This last consideration The Wing, which' is of prime importance for, obviously, failure of the landing gear retraction mechanism will inevitably result in damage or even destruction of the craft.

Those skilled in the art recognize that an aircraft wing is far from a rigid structure; and, infact, must have a high degree of resiliency to withstand Ithe varying forces imposed. g Consequently, the major loads represented by the engines and landing gear cannot be treated as independent entities. Consequently, the fabric is designed so that underall conditions, vibration and stresses will be kept to a practical minimum and the unimpeded operation of movable elements insured. This, in turn, requires a nice mainten- V ance of the interrelationship between the several elements which is obtainable only if over-al1 accuracy is obtained. In this respect the conventional technique is of little value. First, the wing section may be asA much as 100 feet in length and`weigh many tons, so it is diiiicultto move and set up on individual machine tools. lSecond, the distance between dilierent groups is of such magnitude that/measurement with the requisite accuracy is next to impossible. Third, the time required for a number of successive setups is out of reason as -compared with the actual time spent in machining, representing a direct waste of tool capacity and skilled labor. Fourth, it is impossible to provide an integrated support of the wing with the methods heretofore` used, is measured in hundreds of hours; the time spent in using the present apparatus is substantially less than one hour and the results are uniform from assembly to assembly andy accurate per se, distortion is avoided even from the, effects of differing temperatures, which are* inevitable when the machining process extends rover several days.

The present invention comprehends a single machine tool in which the entire Wing section is received and fixedly supported. All the machinin-g operations are then performed without shifting the wing from theoriginal setup. These operations may be performed concurrently and since,l in effect, each individual setup is permanent, accuracy is maintained throughout.

With this and other considerations in view, the invention consists ofthe details of the apparatus and the steps of the method which are disclosed in the specification, claimed in the claims, and illustrated in the accompanying drawings in which:

Figure 1 is a perspective view of one longitudinal half of the device of this invention, the wing section to be machined is indicated in phantom and shown being lowered into position.

Figure 2 is a perspective View of a longitudinal half of the wing section showing the engine attaching pads and the landing gear bushings.

Figure 3 is a further detail of the wing showing the landing gear installation.

VFigure 4 is a side elevation of one of the center towers of the device.

Figure 5 is a detail of the wing piloting means incorporated in the end towers of the device.

Referring to Figure 1, I0 indicates, generally,

a milling machine having a continuous base II to which are secured the center towers I2, intermediate towers I3 and end towers I4 Since only Y half of the device is shown, as it is longitudinally symmetrical, but one of-each of these towers is indicated, and a large part of the intermediate tower I3 is broken away to show the mechanism behind it. In addition, the base supports four separate machine tool batteries, generally indicatedy as I5 for the outboard and I6 for the inboard batteries, two outer wing support columns I1 and two center wing support columns I8 connected to the center towers I2. A platform I9 extends between the several towers to permit ready inspection of the upper part 0f the'wing.

The wing section 26 to be machined is shown in phantom in Figures 1 and 4 and in some details in Figures 2 and 3. It is of conventional structure having the skin 2I and spars 22, transverse bulkheads 23 and several longitudinal webs 24 adjacent that portion of the wing in which the landing gear 25 isretracted. The longitudinal stringers supporting the skin are omittedfrom the showing in the interest of clarity. The bush ings which support the landing gear support shafts 21 and 23 are attached to and extend through these websA and are arranged in two transversel alignmentsthree at 26 for the inboard shaft 21 and two at 30 for the outboard shaft 28. Y actuating cylinder anchor 33 are secured to the inboard shaft 21. lThe actuating cylinder 34 and actuating link 35 lare mounted on the outboard shaft 23. It will be noted that certain of the bulkheads 23 are cut away as at 36, and a large aperture 31 is formed in the lower skin, so the wheel 33 may be retracted to the interior of the wing. Reference to copending applications, Serial Nos. 463,267 and 487,279 will clarify the oonstruction.

In addition to these ten bushings 29 and 36, which are located interiorly of the wing, there are four attachment pads for each engine mount identified as the upper inboard pads 40, lower inboard pads 4I, upper outboard pads 42 and lower outboard pads 43. Each pad is a forging which has been permanently secured as a part of the wing fabric. The upper pads have a single bolt hole 44, while the lower pads each have four bolt holes 45. Each of these holes in all) must be drilled and reamed. In addition, the faces of each pad (16 in number) must be milled. Finally, 10 landing gear bushings must be bored and spot-faced. All these surfaces must be 1inished in precise inter-relationship even though some are located on the leading edge of the wing section (in different parallel planes), others on the lower skin (in planes normal to the above),

The shock strut 3l, brace 32 andv and the remainder are obllquely arranged in the interior of the wing.

Returning to Figure l, the end towers I4 have a vertically mounted rotatable screw 46 engaging the end carriage 41, slidably mounted in the gibs 48. Conventional drive means (not shown) pro- Vide controlled rotation of thescrewv46 and consequent vertical displacement of the carriage 41. As shown in detail in Figure 5, pairs of pins are slidably mounted at the top and bottom oi the carriage in bushings 5| and have a rack 52 meshing with a pinion 53, driven by the crank 54. These pins 5B are so located that they will engage the holes 55 at the corners of the wing-tip attaching angle 55 at the outer ends of the wing section and support and pilot the section on the end carriages 41. Before placing the wing section 20 in the machine, the carriages 41 are run to the top of the screw 46. The wing is then lowered between the two carriages and aligned with them. The crank 54 is then operated advancing the pins 50 and locking the wing section securely between the two end carriages.

The center towers I2 and intermediate towers to the threaded control rod and the other of f which (in the case'of the center towers) has a ball locater 6I. The towers also support an upper and lower clamping blocks 62 on the threaded rods 63, which traverse the tower and are operated by the handwheels 64. In conjunction with the center towers, a center wing support column 40 I8 extends transversely under the space to be occupied by the wing. This has an angle 65 rigidly set, so its base 66 conforms to the lower leading`edge of the wing section when properly set up for machining and its leg 16 similarly de- 5 fines the lower skin surface. A plate 68, level with the base 66, supports the upper leading edge ofthe section.

As described in the copending applications referred to above, the pilot sockets 69 are attached to the wing section in the process of manufacture and serve thereafter to position the wing on assembly bucks through the fuselage assembly steps, as shown in copending application Serial u No, 463,266and the application for Mating fixture 55 filed herewith. These serve as the sole support for the wing through the fuselage assembly stages and the retaining forces applied on them in this milling machine will duplicate those obtaining on the mating bucks. The wing will be subject to the same deflection in each case. Accordingly, after the wing section has been engaged between the end carriages 41, these are lowered until the bottom-,leading edge of the wing -is seated in the angle 65, as shown in Figure 4. The lower clamping blocks 62 are then advanced to hold it in place. The armsr 58 are then swung over the wing section and lowered until the ball locaters 6 I are seated in thesockets 65. The control rods 66 are then adjusted until the upper leading edge of the section rests securelyvon the plates 68, and on tightening the upper clamping blocks 62 the whole wing section is locked in a predetermined position having selected deection characteristics. The same procedure is then folmwed at the intermediate towers Iabut here the Y tool.

purpose is not so much to pilot the section as to provide an auxiliaryfsupport between the prime ylocating points at, 41 and I8. The outer Wing support columns I1 are provided as a safetymeasure to prevent the end carriages being lowered too far and overstressing the section in the long span between 41 and I8. The wing section is now set up for the machining operations.

Attention is now directed to the tool batteries I5 and I6 shown in Figure 1. Eachincludes a base 1I having a low section 12 and a high section 13.4 A carriage 14 is mounted on the section 12 in the slidevvaysl 15 for limited longitudinal movement andfcarries a pair of integrated vertical slides 16 and a pair of horizontal slides 11. Each vertical slide 16 drivingly supports an end mill 18 and a combined drill and reamer 19 designed tovface an upper pad 40 or 42 and finish the bolt hole 44. Each horizontal slide 11 drivingly supports anotherend mill 80 and a gang of four drill and reamers 8I adapted to face a lower pad 4| or 43 and finish the bolt holes 45. The; carriage 14 moves between two predeter-l mined longitudinal positions, inthe iirst of whichV the faces of the four pads are milled and, in the second, the bolt holes in the padsvare first drilled and then, rea'med by a further advance of the The high section 13 Yof the outboard battery I5 has a carriage 82 mounted on the slideways 83 for transverse movement which supports a vertical slide 84. A tool arm 85, is mounted on the slide 84 and a combined boring tool 8B, and end mill 81 is drivingly attached above and below the Y arm adjacent its end. The transverse travel permits the carriage 82 and associated tool arm y 85 to be advanced into the interior ofthe wing through the aperture 31 until the tool is in Vertical alignment with the outboard bushings 30 as governed by a stop at the end of the slideway 83. The s1ide.84 is thenraised until the upper boring tool 86 enters and finishes the rear bushing 30 and continues until the end mill 81 is fed against and faces the inner end surface` of the bushing.` The slide is then lowered and the same process repeated with the lower tool on the front bushing 30. Y

The innerY battery I6 differs from the outer battery only in the construction of the tools for finishing the landing gear bushings necessitated by the fact that there are three rather than two aligned bushings to be finished. In this case, the high sectionr10 has a carriage 9| on slideways 92 supporting a vertical slideA 93 carrying anupper and a lower toolarm 94 and 95. Similar combined boring and milling tools 96 are drivingly mounted above and ybelow each tool arm. The feeding operation is similar to that described above, except that when the slide 93 is raised,

the'A center and rear bushings 29 are bored and the forward faces of these bushings finished. When the slide is lowered, the forward bushing 29 is bored and the rearward faces vof the center and front ,bushings finished. In either case, after the nishing is completed, the tool arms are 4centered vertically and withdrawn trans' versely from Within the wing, the arms 58 disengaged and swung into the clear, the clamping blocks 62 released,-'and the end carriages 41 raised to lift the wing section clear of the machine. It may thenbe picked up lby an over-4 head'crane to continueV through subsequent assembly steps.

- The construction details of the several milling movement orl independent vertical tion disclosed.` l,In the mainthesc machine tools are builtfaccording to standard practice and are, ofi-course, equipped with individual electric motor drives as at 88. vThe tool heads, per se, on the arms 85, 94 and 95, or 16 and 11 are conventional asto drive and feed. In fact, one of the features of the machine is that it may be readily built up from availablestandard tool components,

The yadvantages derived from the use of this machine are twofold: Saving in time of operation and increase in accuracy. Obviously, but one setup isrequired and this, thanks to the piloting means provided, can be completed in a matter of minutes; Consistent' operation has `,shown that the'necessary machining operations can now be done in less than one hundredth the ytime required with the best prior technique and practice. The; increase in accuracy is not attributable alone to the use of a number of machines mounted on a common base, First, the ymode of support `so the wing will assume the deflected position it will occupy when secured to the fuselage, `insures that the structural relation- Ships `are the same. Second. the practice of dividingthe machining into yseparate groups but including common elements between the groups, is also important. Thus, one setup machines one engine mount and a part of the landing gear mounting, while a second setup takes care of the remainder of the'landing gear mounting and the other engine mount. Thus, the proper relationships `between both engine mounts and the landing gear mounting, is obtained. The principle may, of course, be adapted to other specific constructions as well. f

Some changes. may be made `in the arrangement, construction and combination of the various parts of the improved device, without departing` from theV spirit the intention to cover by the claims such changes as may reasonably be included Within the scope thereof.

The invention claimed is:

l. In v'amachine tool particularly adapted to the finishing of av plurality of separated surfaces on 'an aircraft wing, comprising, a base, end

towers on said base, a carriage on each tower adapted to engage one. end of an aircraft wing to be supported between said towers, a pair of intermediate horizontal means on vsaid base spaced on either side of the center of said base and adapted to'secure said wing with the chord thereof substantially vertical, means at said horizontalsupporting means to impress a force on said wing substantially normal to said chord, a plurality of lmetalY cutting tools mounted on said base'intermediate said end towers and said horizontal supporting means, said metal cutting tools including certain cutters mounted for common horizontal movement along the extent of said wingand for independent horizontal transverse Y movement into cutting engagement with said wing, and other cutters mounted for horizontal movement projecting them into the interior of said wing and for vertical movement to engage such other cutters in cutting contact with an internal surface of said wing.

2.. In a milling machine particularly adapted to the inishing ofv a plurality of separated surfaces on an aircraft Wing, comprising, a base, end towers on said base, carriages vertically movable on vsaid -endtowers and adapted to engage the of the invention, and it is' ends of a wing to be supported therebetween with its chord 'substantially vertical, horizontal supporting means intermediate said end tower and including means to impress a force on said wing supported between 'said end carriages substantially normal to the chord thereof, va'plurality of machine tools mounted on said base intermediate said towers and said horizontal supporting means and including machine tool having horizontal and vertical power cuttersV adapted to engage and to finish related horizontal and vertical surfaces on the exterior of vsaid wing, certain of said cutters being .mounted for common horizontal movement longitudinal of said wingand for. independent'movement vertically and transversely horizontally. for cutting engagement with said surface, and otherl cutters mounted for horizontal movement to project said cutters into the interior of said wing and for vertical movement thereafterto fbring said cutters in cutting contact Awith an internal surface of said wing. l

3. In a millingv machineparticularly adapte tov finishing a pluralityof separate surfaces .on an aircraft-wing including those on the leading edge and the main surface of said wing and other surfaces disposed internally of saidwing comprising, a base, a pair of supports at they opposite ends of said base adapted-to engage said wing therebetween and supported with its chord substantially perpendicular, horizontal supporting means intermediate said end towers and including means to impress a force substantially normal to said chord, a plurality'o-f machine cutting tools mounted on said ibase intermediate said end towers, certain of said machine cutting tools being mounted for common movement longitudinally of said wing to perform successive machining operations on said edge and surface portions, other cutting tools mounted for horizontal movement transversely of said Wing to be projected into the interior of the wing and then moved vertically therein to finish said internal surfaces to be withdrawn horizontally from within said wing to permit removal thereof from said ma-` chine. l i

4.y In a milling machine particularly adapted to the machiningof a plurality of separated portions of anaircraft wing, comprising, a base, a pair of end towers on said base, a carriage mounted for vertical movement on each said end tower, one of said carriages adapted to engage each opposite end of an aircraft Wing to be supported therebetween with itsV chord substantially vertical, horizontal supporting means intermediate said towers including means engaging said wing and adapted to impress a force substantially normal to the chord thereof, a plurality of metal cutting machine tools mounted onV said base intermediate said end towers and saidsupporting means, certain of said cutting tools being mounted on said base forV common movement longitudinally of said wing to perform successive cutting operations on portions thereof on the edge and surface of said wing, and other cutting means mounted on said base for common movement transversely of said wing vand including other cutting tools projectable horizontally into the interior of said wing and thereafter movable vertically to bring said other cutting tools into cutting engagement with internal surfaces on said wing to be finished thereby.

5. In a milling machine particularly adapted to the substantially simultaneous finishing of engine mounting means on the exterior of an aircraft Wing and landing gear bushing means in the interior of said wing-comprising, a base, en'd towers on said base, a carriage mounted for vertical movement on each said end towers, said carriages adapted to engage the opposite ends of a Wing to be supported therebetween with its chord substantially vertical, a horizontal supporting means intermediate said end towers adapted to secure said `wings in predetermined horizontal positions, means co-operating with said horizontal supporting means to impress a force on said wings substantially normal yto the chord thereof, a' plurality of machine tools mounted on ysaid base intermediate said end towers and vsaid supporting means, certain' of said "machine tools vbeing mounted for-'joint movement longitudinally of said wingto perform successive operations on said enginev mounting means, other' of said machinev tools being mounted for joint horizontal movement-transversely of said wing andcarrying cutting tools to be inserted into the interior of the said'wing to finish said landing gear bushings, said lastnamed vtools v`beingalso `mounted forvertical movement to engage Said tools in cutting engagement with-said bushings. 1 l6. In a milling machine particularly adapte to the simultaneous machining of a plurality ofv surfaces on the exterior and in the interior of an aircraft wing, comprising, a base, a pair of end towerson said base, a carriage mounted on each said end towers for `vertical movement, means on said carriage to engage thevopposite ends of a wing to be supported therebetween with its chord substantially perpendicular to said base, intermediate supports for Ysaid wingcomprising a fixed angle to engage horizontally one edge of said Wing and a plate level with the horizontal support of said angle to receive the other edge of said wing, an arm rotatably mounted at ther top of said lsupporting means and including pilot-means adapted-to :engage said Wing adjacent an opposite edge on the same side as. said angle, means Onsaidintermediate support torforce said wing into engagement with said angle andsaid pilot means, a pluralityvof machine tools fixed to said base intermediate -said end towers and said supporting means, cer.- tain of said tools being designed to operate on an edge and a surfacecf said wing,other of said tools beingmovable horizontally to project into and be .withdrawn from the interiorof said wing, all said machinev toolsbeing interlocked with respect to said supporting means` and said end towers to finish said plurality of vsurfaces in predetermined interrelationsloip V7. In a milling machine for an aircraft Wing, a base, end towers on Asaid base, means on said endtowers securing said wing at opposite ends thereof and supporting yit with its chordsubstantiallyv perpendicular, intermediate supports on said base between said end towers andcomprising ananglehaving a Ybase mounted at predetermined'elevation andra leg in predetermined alignmenty adapted fto engage one edge of said wing in predetermined alignment, a horizontal support adapted to slidably receive another edge of said wing adjacent said first edge, an arm pivotally mounted on theAtopy of said intermediate support and including a pilot means at the end thereof to engageanedge of said wing opposite said first edge, and means'carrie'd by said supporting means, and engaging a surface opposite that engagednby said pilot meansand said angle to force said wing into engagementy when en eers 'eel-Samuele while@- maining in contact -with said horizontal support.

8. In a milling machine particularly adapted to the milling of finished surfaces on an aircraft wing, comprising,y a base, end towers on said base, a carriage movably mounted on eachV adapted to engage the other side of said wing and exert a force thereon substantially normal to the chord thereof to move said wing into engagement with said pilot means and said alignment means, and a plurality of machine tools arranged on said base intermediate said end ltowers and comprising cutters adapted to perform successive operations on the edge and sur- `face of said wing, and retractable cutters adapted to be projected into the interior of said Wing and finish surfaces located interiorly thereof and withdrawn when said surfaces are machined to permit vertical movement of said wing on said end carriages to remove said wing from said milling machine.

WILLIAM F. PIOCH.

JOHN W. MISTELE. I 

